Evaluation of Potential DnaK Modulating Proline-Rich Antimicrobial Peptides Identified by Computational Screening

Thomas N G Handley; Wenyi Li; Nicholas G Welch; Neil M O'Brien-Simpson; Mohammed Akhter Hossain; John D Wade

doi:10.3389/fchem.2022.875233

Evaluation of Potential DnaK Modulating Proline-Rich Antimicrobial Peptides Identified by Computational Screening

Front Chem. 2022 Apr 13:10:875233. doi: 10.3389/fchem.2022.875233. eCollection 2022.

Authors

Thomas N G Handley^{1

2}, Wenyi Li³, Nicholas G Welch¹, Neil M O'Brien-Simpson³, Mohammed Akhter Hossain^{1

2}, John D Wade^{1

2}

Affiliations

¹ The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia.
² School of Chemistry, University of Melbourne, Parkville, VIC, Australia.
³ ACTV Research Group, Centre for Oral Health Research, Melbourne Dental School, University of Melbourne, Melbourne, VIC, Australia.

Abstract

The day is rapidly approaching where current antibiotic therapies will no longer be effective due to the development of multi-drug resistant bacteria. Antimicrobial peptides (AMPs) are a promising class of therapeutic agents which have the potential to help address this burgeoning problem. Proline-rich AMPs (PrAMPs) are a sub-class of AMPs, that have multiple modes of action including modulation of the bacterial protein folding chaperone, DnaK. They are highly effective against Gram-negative bacteria and have low toxicity to mammalian cells. Previously we used an in silico approach to identify new potential PrAMPs from the DRAMP database. Four of these peptides, antibacterial napin, attacin-C, P9, and PP30, were each chemically assembled and characterized. Together with synthetic oncocin as a reference, each peptide was then assessed for antibacterial activity against Gram-negative/Gram-positive bacteria and for in vitro DnaK modulation activity. We observed that these peptides directly modulate DnaK activity independently of eliciting or otherwise an antibiotic effect. Based on our findings, we propose a change to our previously established PrAMP definition to remove the requirement for antimicrobial activity in isolation, leaving the following classifiers: >25% proline, modulation of DnaK AND/OR the 70S ribosome, net charge of +1 or more, produced in response to bacterial infection AND/OR with pronounced antimicrobial activity.

Keywords: DnaK inhibition; PrAMP; antibacterial peptides; in silico; solid phase peptide synthesis.